This invention relates to a process for polymerizing conjugated diolefins and more particularly to a process for the non-aqueous dispersion polymerization of a conjugated diolefin monomer in a liquid hydrocarbon dispersion medium with a Ziegler-Natta catalyst in the presence of a block copolymer dispersion stabilizer.
Many polymerization processes are used in the formation of synthetic polymers. Most step-growth polymerization reactions are carried out in homogeneous systems by simple combination of two or more monomers in the melt, in the absence of solvent, i.e., bulk polymerization. The principal advantage of a bulk polymerization process is that the product obtained is essentially free of diluent or impurities and can be used directly. A disadvantage of a bulk polymerization reaction is that it is difficult to control the reaction temperature.
A wide variety of polymerization methods are used in the preparation of chain-growth polymers. The radical chain-growth polymerization of olefin monomers, for example, can be conducted in a number of different types of reaction systems, including bulk polymerization, suspension polymerization, emulsion polymerization and solution polymerization. Each of these systems has certain advantages and disadvantages.
Bulk polymerization is the direct conversion of liquid monomer to polymer in a reaction system in which the polymer remains soluble in its own monomer. As noted above, bulk polymerization systems are free from diluents but the reaction temperature is difficult to control.
In suspension polymerization, the initiator is dissolved in the monomer, the monomer is dispersed in water, and a dispersing agent is incorporated to stabilize the suspension formed. All suspension polymerization processes use some type of surfactant to keep the monomer globules dispersed throughout the reaction in order to avoid coalescence and agglomeration of the polymer. Not only does the suspension stabilizer affect the particle size and shape, but also the clarity, transparency and film-forming properties of the resultant polymer. A variety of dispersing agents including water-insoluble, finely-divided, inorganic materials and organic materials, depending upon the monomer to be polymerized, have been used as dispersing agents. Thus, for example, talc, barium, calcium and magnesium carbonates, silicates, phosphates and sulfates, as well as poly(vinyl alcohol), tragacanth gum, salts of styrene-maleic anhydride copolymers, vinyl acetate-maleic anhydride copolymers and their salts, starch, gelatin, pectin, alginates, methyl cellulose, carboxymethylcellulose, bentonite, limestone and alumina have been used as suspending agents. A major advantage of suspension polymerization is that the polymeric products are obtained in the form of small beads which are easily filtered, washed and dried. For reasons of cost and nonreactivity, water is a much more desirable diluent and heat-transfer medium than most organic solvents. However, in certain catalytic polymerization processes, such as, for example, in the Ziegler-Natta catalyzed polymerization of a conjugated diolefin such as, for example, butadiene-1,3 and isoprene, the presence of any moisture is highly undesirable. Thus, suspension polymerization is not an effective process for the Ziegler-Natta catalyzed polymerization of conjugated diolefins such as butadiene-1,3 and isoprene.
An emulsion polymerization process is considered to be a three-phase reaction system consisting of large droplets of the monomer, the aqueous phase containing the dissolved initiator, and the colloidal particles of monomer-swollen polymer. While the emulsion polymerization process has the economic advantage of using water as the emulsion base, not all polymerization processes can tolerate the presence of water. Such is the case with the Ziegler-Natta catalyzed process for polymerizing butadiene-1,3 and isoprene.
In solution polymerization, an organic solvent is used which is capable of dissolving the monomer, the polymer and the polymerization catalyst or initiator. Inasmuch as the polymer is soluble in the organic solvent which is used, there is a tendency for the viscosity of the solution to increase as the molecular weight of the polymer increases. If this continues over a period of time, the solution becomes too viscous to handle in conventional polymerization reaction systems unless the solids content is limited to a low level. In commercial polymerization processes, it is desirable to obtain a polymerization mass which has a high concentration of solid polymer and, at the same time, comprises a material which is easy to handle and does not agglomerate on the walls of the reaction vessel.
Many of the polymerization processes described in the prior art relate to bulk, suspension, emulsion, or solution polymerization. These prior art processes do not possess the advantageous characteristics of the non-aqueous dispersion polymerization process of the present invention.
In U.S. Pat. No. 3,047,559 to R. H. Mayor et al (The Goodyear Tire & Rubber Company), a polymerization process is disclosed for polymerizing isoprene in the presence of a catalyst comprising a complex product of titanium tetrachloride and an organoaluminum compound or an etherate of such organoaluminum compound. The polymerization reaction is conducted either in a bulk process, a solution process or by contacting vapor of the monomer with the catalyst. When a solution process is employed, saturated hydrocarbon solvents, e.g., pentane, hexane, cyclohexane and benzene, are preferred. While this patent discloses a Ziegler-Natta catalyst, the process described in the patent does not employ a dispersion stabilizer and thus does not produce the desirable fluidity characteristics of a high solids content product obtained by the non-aqueous dispersion polymerization process of the present invention.
In U.S. Pat. No. 3,114,743 to S. E. Horne, Jr. (Goodrich-Gulf Chemicals, Inc.), a solution polymerization process is described for polymerizing isoprene to substantially cis-1,4-solid polyisoprene. According to the patent, monomeric isoprene is polymerized in the presence of a liquid hydrocarbon solvent containing a catalyst consisting essentially of the composition produced by adding to said solvent (a) a titanium tetrahalide and (b) a trialkyl aluminum wherein each alkyl group contains from 2 to 8 carbon atoms, in proportions of (a) and (b) such as to provide in said catalyst a molar ratio of titanium to aluminum of 0.5:1 to 1.5:1. The hydrocarbon solvent can be a saturated alkane such as hexane, heptane and cetane; a cycloalkane such as cyclohexane or methyl cyclohexane; or a benzene hydrocarbon such as benzene, toluene or xylene. While the catalyst in this patent is of the Ziegler-Natta type, the polymerization system is a solution polymerization system. It is noted that with heptane as the solvent, the solution becomes viscous in one hour or less and that the viscosity of the solution continues to increase during a two hour interval until the solution becomes quite viscous. Such an increase in viscosity is undesirable in a commercial process in that viscous materials are difficult to handle. In addition, more energy is required to separate the desired polymer product from a viscous material than from a material which is fluid. The polymer obtained in the Ziegler-Natta non-aqueous dispersion process of the present invention can be readily separated from the dispersion medium.
In U.S. Pat. No. 3,178,402 to D. R. Smith et al (Phillips Petroleum Company), a polymerization process is disclosed for polymerizing butadiene-1,3 in the presence of a catalyst comprising (a) a trialkyl aluminum and (b) a titanium tetraiodide. The polymerization is conducted either in a bulk process or a solution process. When a solution process is employed, various diluents including propane, n-butane, n-pentane, isopentane, hexane, isohexane, isooctane, n-decane, benzene, toluene, xylene, ethylbenzene, cyclohexane, and mixtures thereof can be employed. While the catalyst in this patent may be considered of the Ziegler-Natta type, the patent does not disclose a non-aqueous dispersion polymerization process and does not employ a dispersion stabilizer. The process described in the patent, therefore, does not have the fluidity advantages of a high solids product obtained by the non-aqueous dispersion polymerization process of the present invention.
In U.S. Pat. 3,910,869 to M. C. Throckmorton (The Goodyear Tire & Rubber Company) and U.S. Pat. 3,856,764 to M. C. Throckmorton et al (The Goodyear Tire & Rubber Company), solution polymerization processes are described for polymerizing conjugated diolefins, particularly 1,3-polybutadiene to form polymers containing cis-1,4 polybutadiene by polymerizing the conjugated diolefin in inert solvents with a complex catalyst system. The preferred solvents are hexane and benzene. The complex catalyst system comprises (1) organoaluminum compounds, (2) nickel compounds from the group of carboxylic acid salts of nickel, organic complex compounds of nickel, or nickel tetracarbonyls, (3) fluorine-containing compounds selected from the group of hydrogen fluoride or hydrogen fluoride complexes with a member of a class consisting of ketones, esters, ethers, alcohols or nitriles. While the process described in this patent gives a high proportion of cis-1,4 polymer in the polymerization product, the catalyst is somewhat more complex than the normal Ziegler catalyst. This catalyst combination, however, is very useful from a commercial standpoint. These patents are directed to solution polymerization processes and thus do not have the fluidity advantages possessed by the non-aqueous dispersion polymerization process of the present invention.
In U.S. Pat. 3,297,667 to von Dohlen et al (Union Carbide Corp.), there is disclosed a solution polymerization system for polymerizing conjugated diolefins with a catalyst comprising the reaction product (1) an ion of a group IIIb metal in a trivalent state, (2) a bidentate organic ligand, (3) a halide ion, and (4) an aluminum trialkyl or alkylaluminum halide. In U.S. Patent 3,657,205, to Throckmorton (The Goodyear Tire & Rubber Company), there is disclosed a process for the stereospecific polymerization or copolymerization of various conjugated diolefins using a catalyst which is (1) an organoaluminum compound from the class of triorganoaluminum and diorganoaluminum hydrides, (2) an organometal compound, the metal ion of which is selected from group IIIb, and (3) a compound providing a halide ion. This patent, like U.S. Pat. No. 3,297,667, teaches a solution polymerization with a catalyst somewhat more complex than a Ziegler-Natta catalyst. Thus, the polymerizations do not possess the fluidity advantages that are obtained by the non-aqueous dispersion polymerization process of the present invention.
In U.S. Pat. No. 3,170,907 to Ueda et al (The Bridgestone Tire & Rubber Company, Ltd.), there is disclosed a process for the manufacture of cis-1,4-polybutadiene which comprises polymerizing butadiene in a hydrocarbon diluent with a reaction system obtained by mixing three components consisting of (a) an organic carboxylic acid salt of nickel, (b) boron trifluoride etherate, and (c) trialkylaluminum. Like the Throckmorton patents previously mentioned, this catalyst system is more complex than a Ziegler-Natta catalyst but is suitable from a commercial standpoint to produce high cis-1,4-polybutadiene.
British Pat. No. 827,365 (Goodrich-Gulf Chemicals, Inc.) is similar to U.S. Pat. No. 3,114,743 discussed hereinabove, but includes not only heavy metals in the 4th to 6th positions, but also heavy metals up through the 10th position in the Periodic Table. While the catalyst disclosed in this patent is of the Ziegler-Natta type, the polymerization system is a solution polymerization system. The solution becomes viscous in a short period of time. As time continues to pass, the viscosity of the solution continues to increase. The patent does not disclose a non-aqueous dispersion polymerization process and does not employ a dispersion stabilizer. The process described in the patent, therefore, does not have the fluidity advantages of a high solids product obtained by the non-aqueous dispersion polymerization process of the present invention.
British Pat. No. 872,283 (Goodrich-Gulf Chemicals, Inc.) discloses a solution polymerization process for polymerizing isoprene in butane with a Ziegler-Natta catalyst system at a temperature below 10.degree. C. The process disclosed in this patent does not employ a dispersion stabilizer and thus does not possess the advantages of the non-aqueous dispersion polymerization process of the present invention.
In Industrial and Engineering Chemistry 51, 19-22 (1959), Natsyn Pilot Plant, by C. T. Winchester (The Goodyear Tire & Rubber Company), a plant is described for the polymerization of isoprene in n-pentane with a Ziegler-Natta catalyst at a temperature of 50.degree. C. The process described in this article is a solution process and does not employ a dispersion stabilizer. The process thus does not have the advantages of the non-aqueous dispersion polymerization process of the present invention.
For other examples of the solution polymerization of conjugated diolefins with other Ziegler-Natta catalyst systems, see U.S. Pat. Nos. 3,438,958 (Throckmorton), 3,446,787 (Throckmorton et al), 3,446,788 (Throckmorton et al), 3,483,177 (Throckmorton et al), 3,528,957 (Throckmorton et al), 3,541,063 (Throckmorton et al), 3,462,405 (Schoenberg), 3,652,529 (Judy et al), 3,734,900 (Throckmorton et al), and 3,813,374.
The references discussed above are relevent to the process of the present invention inasmuch as they relate to the polymerization of a conjugated diolefin monomer in the presence of an inert solvent with a catalyst system containing at least an organoaluminum compound and some sort of a transition metal compound. The catalyst of the references discussed are, for the purposes of this application, to be grouped under the broad terminology of Ziegler-Natta type catalyst. It should be appreciated, however, that the references discussed above are either bulk polymerizations or true solution polymerization processes. None of the aforementioned references disclose a process for the non-aqueous dispersion polymerization of conjugated diolefin monomers in a liquid hydrocarbon dispersion medium with a Ziegler-Natta catalyst in the presence of a block copolymer dispersion stabilizer in accordance with the process of this invention.
There are other references that disclose catalytic non-aqueous dispersion polymerization of olefins but either the process does not employ a Ziegler-Natta catalyst or the process does not relate to the polymerization of a conjugated diolefin. Such is the case with British Pat. Nos. 941,305; 1,007,476; 1,008,188; 1,123,611; and 1,165,840; Belgian Pat. No. 669,261; South African Pat. No. 72/7635; and Netherlands Pat. Nos. 65/11663 and 72/06366.
British Pat. No. 941,305 (Imperial Chemical Industries Limited) relates to stable dispersions of synthetic polymers in an organic liquid wherein the disperse particles of polymer are stabilized by a block or graft copolymer. One constituent of the stabilizing copolymer is solvated by the organic liquid; the other constituent of the copolymer forms an integral part of the polymer particles. The soluble constituent is irreversibly attached to the disperse particle through chemical bonds. Where the disperse polymer is polar, e.g., methyl acrylate, the organic liquid is non-polar, e.g., aliphatic hydrocarbon. Where the disperse polymer is non-polar, e.g., styrene, vinyl toluene or polyisoprene, the organic liquid is polar, e.g., ethyl alcohol, methyl alcohol, or acetone. The block copolymer stabilizer can be preformed or it can be formed in situ during formation of the disperse particle. The block copolymer preferably contains one constituent which is identical with, or closely related to, the polymer to be produced. For example, where the disperse polymer is styrene, the compatible constituent of the block may be styrene or a copolymer of styrene and vinyl toluene. There is no disclosure of a Ziegler-Natta catalyst in this patent. This patent does not disclose a process for the non-aqueous dispersion polymerization of a conjugated diolefin monomer with a Ziegler-Natta catalyst in accordance with the process of the present invention.
British Pat. No. 1,007,476 (The Firestone Tire & Rubber Company) relates to a process in which at least one ethylenically unsaturated monomer is contacted with an anionic polymerization catalyst, e.g., butyllithium, in an organic liquid, said liquid having dissolved therein a polymeric substance as a suspending agent and said liquid is a non-solvent for the polymer produced by the process. Isoprene is one of the substances which can be polymerized by the process. Organic solvents which are disclosed include saturated and unsaturated aliphatic and cycloaliphatic hydrocarbons containing from 3 to 30 carbon atoms, e.g., propane, butane, isobutane, pentane, isopentane, hexane, butene-1, cyclohexane, mineral oil, kerosene, etc. The dispersing agent must be at least partially soluble in the organic medium. Examples of dispersing agents include polymers and copolymers of conjugated diolefins which contain 4 to 6 carbon atoms, e.g., polybutadiene-1,3, polypiperylene, polyisoprene, and copolymers of such diolefins with a styrene monomer, e.g., styrene and alpha-methyl-styrene. Other dispersing agents include copolymers of ethylene and propylene, copolymers of isobutylene and isoprene and copolymers of isobutylene and styrene. In reviewing the prior art, this patent discloses that a Ziegler catalyst is undesirable because of catalyst contamination in the polymer product. This patent does not disclose a process for the non-aqueous dispersion polymerization of a conjugated diolefin monomer with a Ziegler-Natta catalyst in accordance with the process of the present invention.
British Pat. No. 1,008,188 (The Firestone Tire & Rubber Company) is similar to British Pat. No. 1,007,476 except that the monomer which is polymerized according to this patent is a vinyl aromatic compound, e.g., styrene. The catalyst is an anionic polymerization catalyst e.g., butyllithium. The organic liquid in which the reaction is conducted is a non-solvent for the polymer produced by the process. The organic liquid has a dispersing agent dissolved therein, said dispersing agent being a polymer or copolymer of a conjugated diolefin which contains 4 to 6 carbon atoms, e.g., polybutadiene-1,3; polypiperylene, and copolymers of such diolefins with a styrene monomer, e.g., styrene and .alpha.-methylstyrene. Other dispersing agents are copolymers of ethylene and propylene, copolymers of isobutylene and isoprene and copolymers of isobutylene and styrene. The organic liquid includes saturated and unsaturated aliphatic and cycloaliphatic hydrocarbons containing from 3 to 30 carbon atoms, e.g., propane, butane, isobutane, pentane, isopentane, hexane, butene-1, cyclohexane, mineral oil, kerosene, etc. In reviewing the prior art, this patent discloses that a Ziegler catalyst is undesirable because of catalyst contamination in the polymer product. This patent does not disclose a process for the non-aqueous dispersion polymerization of a conjugated diolefin monomer with a Ziegler-Natta catalyst in accordance with the process of the present invention.
British Pat. No. 1,123,611 (Imperial Chemical Industries Limited) relates to a process of forming stable dispersions of a polymer with a free-radical initiator in an organic liquid in which the polymer is insoluble, said process comprising the polymerization of at least one ethylenically unsaturated monomer in the organic liquid in the presence of a preformed dispersion stabilizer. The stabilizer comprises the product of a condensation reaction between (a) at least one component which has a molecular weight of from 500 to 5000 and is solvatable by the organic liquid and contains a group capable of a condensation reaction and (b) another component which has a molecular weight of at least 250 and is of different polarity from the solvatable component and relatively non-solvatable in the organic liquid and contains a group capable of a condensation reaction with the solvatable component. The weight ratio of (a) to (b) is from 0.5:1 to 5:1. The stabilizers disclosed in the patent are different from those employed in the process of the present invention. Ziegler-Natta catalysts are not disclosed in the patent. Therefore, this patent does not disclose a process for the non-aqueous dispersion polymerization of a conjugated diolefin monomer with a Ziegler-Natta catalyst in accordance with the presence of the present invention.
British Pat. No. 1,165,840 (Hercules Incorporated) relates to a process for obtaining a colloidal dispersion of a propylene homopolymer or copolymer of propylene with an alpha olefin having 2 to 20 carbon atoms or with styrene in an inert hydrocarbon diluent such as n-heptane and kerosene. The polymerization catalyst comprises a Ziegler-Natta catalyst. When preparing a colloidal dispersion of polypropylene, it is necessary first to prepare a colloidal trivalent titanium catalyst and then use this colloidal trivalent catalyst in combination with an aluminum alkyl to polymerize the propylene and obtain the colloidal dispersion. Thus, an alpha-olefin containing at least 6 carbon atoms, e.g., octene-1 is polymerized with a trivalent titanium-containing catalyst and a dialkylaluminum halide catalyst activator in the presence of a liquid hydrocarbon. The catalyst dispersion thus formed is used to polymerize propylene or a mixture of propylene and a comonomer which is an alpha-olefin containing 2 to 20 carbon atoms or styrene. A solid, colloidally dispersible propylene polymer product is recovered. This patent does not disclose a process for the non-aqueous dispersion polymerization of a conjugated diolefin monomer with a Ziegler-Natta Catalyst in accordance with the process of the present invention.
Belgian Pat. No. 669,261 (Imperial Chemical Industries Limited) is similar to British Pat. No. 1,165,840 in that it relates to a process for the dispersion polymerization of ethylene using a dispersion of a Ziegler-Natta catalyst in aliphatic hydrocarbons. The patent does not disclose the Ziegler-Natta non-aqueous dispersion polymerization of a conjugated diolefin in the presence of a block copolymer dispersant in accordance with the process of the present invention.
South African Pat. No. 72/7635 (Imperial Chemical Industries Limited) relates to an anionic initiated (metal hydrocarbyl, e.g., alkyl lithiums and alkyl sodiums) non-aqueous dispersion block polymerization of a polymeric material in a diluent wherein at least one polymer block is insoluble in said diluent and which forms at least part of the core of the final polymeric product and another block which is solvated by the diluent and which provides stabilization for the final polymerization product. Diluents include aliphatic hydrocarbons having from 3 to 10 carbon atoms, aromatic hydrocarbons, e.g., benzene and toluene, and cycloaliphatic hydrocarbon, e.g., cyclohexane. This patent includes butyllithium-initiated non-aqueous dispersion polymerization of conjugated diolefins where the dispersant can comprise three blocks; block "A" can be polymerized t-butyl styrene; block "B" can be polymerized butadiene, isoprene or n-butyl styrene; and block "C" can be polymerized styrene, vinyl pyridine, divinyl benzene, a styrene-divinyl benzene mixture, methylmethacrylate, ethyl acrylate, dimethylaminoethyl methacrylate or methacrylonitrile. This patent does not disclose the Ziegler-Natta polymerization process of the present invention.
Netherlands Patent No. 65/11663 (Imperial Chemical Industries Limited) relates to the non-aqueous dispersion polymerization of methyl methacrylate, styrene, lauryl methacrylate, glycidyl methacrylate and combinations of methacrylates. Stabilizers include long chain paraffinic acids, esters of fatty acids or diacids, fatty acid esters of acrylic or methacrylic acid, long-chain poly(vinyl esters), polyolefins, or polydiolefins. Addition polymers are formed with a Ziegler-Natta catalyst. The polymer is grafted onto a soluble polymer. The process of the patent does not employ block copolymers in accordance with the process of the invention. There is no disclosure in the patent of a process for the non-aqueous dispersion polymerization of a conjugated diolefin monomer in a liquid hydrocarbon dispersion medium with a Ziegler-Natta catalyst in accordance with the process of the present invention.
Netherlands Pat. No. 72/06366 (Mobile Oil Company) relates to the non-aqueous dispersion polymerization of styrene using a block copolymer as the dispersing agent. The dispersion medium can be an aliphatic hydrocarbon containing 4 to 7 carbon atoms including butane, pentane, isopentane, hexane and heptane. Isoprene is disclosed as a suitable monomer in forming a block copolymer dispersant for the polymerization of styrene. While a Ziegler-Natta catalyst is disclosed in connection with the formation of a conjugated diolefin as a dispersing agent, there is no disclosure wherein the main polymer is formed by the Ziegler-Natta polymerization of a conjugated diolefin monomer in the presence of said dispersing agent. This patent, therefore, does not disclose the non-aqueous dispersion polymerization process of the present invention.
The references reviewed hereinabove fail in one or more respects to teach or disclose the process of the present invention. In summation, some of the references disclose bulk or solution (but not non-aqueous dispersion) polymerization of a conjugated diolefin monomer with a Ziegler-Natta catalyst. Other references disclose non-aqueous dispersion polymerization of olefins (but not conjugated diolefins) with a Ziegler-Natta catalyst. Still other references disclose non-aqueous dispersion polymerization of conjugated diolefins with an anionic catalyst, i.e., butyllithium (but not a Ziegler-Natta catalyst). Still other references disclose non-aqueous dispersion polymerization wherein the polymer is grafted onto a soluble polymer but not wherein the dispersant is a block copolymer as employed in accordance with the process of the present invention.
As reported hereinabove, the polymer of a conjugated diolefin monomer, such as, for example, poly-cis-1,4-isoprene has been obtained previously in a solution polymerization process wherein isoprene is polymerized in a solvent such as n-pentane, n-hexane, or n-heptane in the presence of a Ziegler-Natta catalyst. As the molecular weight of the polyisoprene increases in a solution polymerization process, the viscosity of the solution in which the polymer is dissolved also increases. In a short period of time, the polymer solution becomes so viscous that it does not flow and the polymer product plates out on agitator blades and on the walls of the reaction vessel unless the solids content is limited to a low level. In such a solution polymerization process, the limit of solids that can be handled in a commercial reactor system is typically about 10 to about 12 grams of poly-cis-1,4-isoprene per 100 cc of polymer solution, i.e., a solids content of about 14 to about 18 weight percent. If high molecular weight poly-cis-1,4-isoprene could be produced in appreciably higher solids concentrations, considerable savings could be realized in the cost of its production in a given reaction system.
In the non-aqueous dispersion polymerization process of the present invention, a Ziegler-Natta catalyzed process for the polymerization of a conjugated diolefin, such as, for example, isoprene is provided utilizing a block copolymer dispersion stabilizer and a dispersion medium such as n-butane or neopentane. The concentration of the poly-cis-1,4-isoprene in the polymeric product solution is greater than that obtained in a solution-type Ziegler-Natta catalyzed process for the polymerization of isoprene utilizing no dispersion stabilizer and n-pentane as the diluent medium. Whereas a solids content of about 14 to about 18 weight percent is obtained in conventional solution polymerization of isoprene, a solids content of about 25 to about 50 weight percent is obtained in the process of the present invention while the polymerizate particles are finely divided and flowable and the mixture has a much lower viscosity.
It should be appreciated that conjugated diolefins can also be polymerized in solution utilizing lithium metal catalyst or mono-organolithium catalyst or diorganolithium catalyst. These solution polymerizations, like some of the references discussed in this application, are solution polymerizations and they themselves do not possess the fluidity advantages possessed by the non-aqueous dispersion process of the present invention. It should be understood that the polymerization of conjugated diolefins by means of a lithium based catalyst of the prior art are solution polymerization processes. None of the known references disclosed a process for the non-aqueous dispersion polymerization of conjugated diolefin monomers in a liquid hydrocarbon dispersion medium with a lithium based catalyst in the presence of a block copolymer dispersion stabilizer in accordance with the process of this invention. The non-aqueous dispersion process of a lithium based catalyzed polymerization of a conjugated diolefin such as, for example, isoprene or butadiene with, for instance, lithium metal or organolithium compounds such as dilithiostilbene or butyllithium is provided utilizing a block copolymer dispersion stabilizer and a dispersion medium such as n-butane or neopentane. The concentration of the polyconjugated diolefin in the product solution is greater than that obtained in the solution type lithium based catalyzed process for the polymerization of conjugated diolefins utilizing no dispersion stabilizer and n-pentane or n-hexane as the diluent medium. Whereas a solid content of about 14 to about 18 weight percent is obtained in the conventional or prior art solution polymerization of conjugated diolefins with these lithium based catalysts, a solid content of from about 25 up to about 50 weight percent can be obtained in the process of the present invention when the polymerizate particles are finely divided and flowable and the mixture has a much lower viscosity.